[occi-wg] Revisiting Fat Links

[Ralf Nyren]

Michael,

> In trying to digest all the link traffic (great stuff by the way) - can  
> we perhaps assume that any POST or PUT operation would never destroy  
> links.

POST would never destroy data in any of the three proposals. In the simple  
approach (called "Another proposal" in the wiki) a PUT request can indeed  
destroy Links. This is the big disadvantage of that approach. The Thin and  
Fat Link proposals do not have this problem.

> Then, for removal of links, perhaps a separate DELETE call to the  
> resource that specifies (somehow) only the deletion of the listed links  
> is removed?

The problem is, with the simple approach, that you cannot reliable specify  
which Link to delete. Since a Link in this case is a composition of the  
Resource and is not a resource in itself there is no unique identifier.  
What you have is the target URI but there is nothing in the model which  
prevents you from linking multiple times to the same target. E.g.  
attaching two virtual interfaces to the same network. Thus you must  
specify the whole set of Links in every PUT request and any Links not  
present in that set must be removed by the server.

With the Link as a REST resource as in the Thin/Fat Link proposals this is  
not a problem since the normal CRUD operations are allowed on individual  
Links.

regards, Ralf